Generally, in an image-forming apparatus employing an electrophotographic method, image exposure is performed onto a photoreceptor to form a latent image. The formed latent image is then developed to form a toner image, which is then transferred to a transfer sheet and thermally fixed, and thus an image is formed. On the other hand, there remains the toner on the photoreceptor which has not been transferred. The residual toner is cleaned by a blade or the like for utilizing repeatedly the photoreceptor.
As a photoreceptor, those have been employed in which a photosensitive layer is coated on an aluminum support. However, when the photoreceptor has a photosensitive layer to both extreme edges and are not involved in the image formation during development, the toner in the developer adheres onto the charged photoreceptor and the excessive toner is consumed or the adhered toner is scattered which stains the interior of the image-forming apparatus and transfer sheets. In order to minimize these problems, the photosensitive layer on the aluminum support is peeled off or removed, and the electrically conductive aluminum support is exposed so that no toner is adhered at both edges of the photoreceptor. Furthermore, unevenly coating occurs very readily at the edges of the photoreceptor during the manufacturing process, and unevenly coated parts tend to cause peeling and cracking over the whole area of the photosensitive layer.
However, the surface of the aluminum support can be subjected to treatment to result in specular gloss on which a photosensitive layer can be uniformly coated. Accordingly, when the blade of a cleaning device is in contact with the surface, adhesion and frictional force increases. Particularly, for example, when with the rotation of the photoreceptor, the blade is brought into contact in the opposite rotational direction, the edge of the blade follows the surface of the photoreceptor in accordance with the frictional force, and a problem occurs in that the edge of the blade is distorted into a curl shape.
In order to solve this problem, Japanese Patent Publication Open to Public Inspection No. 5-150696 discloses a technique in which when the torque against the cleaning blade by the uppermost layer of the photoreceptor is 4.0 kg.multidot.cm or more, tendency of the curl distortion of the blade edge is minimized by employing a material which enables the reduction of the torque of the edge of the blade by 0.5 kg.multidot.cm or more.
However, the above-mentioned technique is not particularly effective for this problem in that the edge of a fresh blade is curled when being pulled by the photoreceptor. Furthermore, during usage over a long time, the surface is subjected to abrasion by the blade to result in a smooth surface, and as a result, the adhesion with the blade increases. Thus, the above-mentioned technique does not substantially solve the problem.
Furthermore, Japanese Patent Publication Open to Public Inspection No. 6-258995 discloses a technique in which improvement is achieved by the formation of minute unevenness on the surface to decrease the friction coefficient, and proposes that when the minute unevenness is formed, the surface treatment is performed in advance, providing an abrasive means such as a brush or coating a abrasive material. In this technique, the unevenness is formed on the surface and some effect for decreasing friction is realized. However, the toner tends to be accumulated on the unevenness. During long-term use, the toner adheres in the recesses of the formed unevenness and buried in the unevenness while being forcefully pushed with the blade to increase the frictional force which causes a problem in that the blade is curled.